December 10, 2006

Wind energy running out of puff

Writing about web page

What a surprise that this story is only two days old yet I found it hard to dig out the information…

Anyway, a report by the Renewable Energy Foundation (a pro-renewables group) has suggested that claims on wind power have been grossly overstated. Most turbines are marketed as having a certain power output (i.e. a 5MW turbine) in much the same way as a nuclear reactor might be referred to as a 1200MW station etc. What this fails to hit home is that this is their rated power at a rated wind speed, and the figure is easily misleading if you’re not in the know and leads to incorrect direct comparisons. The amount of power generated by a turbine is proportional to the cube of the windspeed, i.e. if you’re generating 5MW at 12m/s wind speed then at a still brisk 6m/s you’re generating a pitiful 625kW. The amount of energy over time you can expect to get from a power generator compared to it’s rated power is typically referred to as the capacity factor or utilisation factor. For wind farms, this utilisation factor is very heavily dependent on siting. There’s the background for you.

The report has found that in the wind sector (which is the most active and the one which most noise is being made about), some turbines are being built on sites with a utilisation factor of as little as 9%. For sites in the North of Scotland and offshore (where we should be building turbines, if at all), the utilisation factor is more like 50%. So ramping up wind power in sensible locations, if that is a route we choose to take, would result in the requirement to build a very large (and expensive) grid connection from Northern Scotland and the surrounding offshore area down to England, where most of our electricity is consumed. You see, it’s not simply a case of plugging it into a grid up in Northern Scotland and wishing the electricity to get to South England – we’re talking about Gigawatts of power here, and as there’s currently no need for such a connection to exist to such remote locations, there isn’t one.

Perhaps even more worrying, the report has built a predictive model of how a large scale network would perform using data collected from Ofgem and hour by hour wind data from the Met Office to predict the performance of such a network in the month of January had it existed for years 1994 to 2004. The results, alarmingly, show that even if wind farms were distributed nationwide, the power variation averages 94% of installed capacity due to wind variation, and the average minimum is 3.7% or 0.9GW in a 25GW wind turbine network. Power swings of 70% over a 30 hour period are the norm. Any person with a grasp of the fundamentals of power generation would take a look at the above and come to the same conclusion I did years ago: wind power is a nonsense for taking up baseload and entrusting security of supply to.

The government, however, doesn’t see this. It’s prediciton is that 75% of the 2010 Renewables target, and the majority of the “20% by 2020” target, will be made from windpower. I should point out at this point that the REF’s report is in keeping with the experiences of other EU nations with wind energy, and not a one-off anomaly.

So, where does this leave us? In the same position I thought we were in before I read the report. We currently are in a situation of increasing demand (and likely to increase dramatically further if the government is serious about us giving up internal combustion to move us about), and rising fossil fuel prices. People are running scared about CO2 emissions as if the apocalypse is approaching. The golden alternatives of wind (as by far and away the biggest hope of the renewables sector) and to a lesser extent other alternatives are inadequate and failing to even live up to their hoped-for minute contribution in the energy mix. Yet we still somehow have to meet our energy demands and ensure security of supply. The solution? Well to me it’s patently obvious – sequestration powerplants and nuclear. The sooner we get the doubters out of their daydreams and get on with some construction before it’s too late to replace our aging plant (we’re due to lose all four of our Magnox stations within four years for example), the sooner we will not have to rely heavily on imports from France and other nations, and the sooner electricity prices will escape the rapidly escalating costs of natural gas.

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  1. Seems like a very easy solution… how about considering the possibilities of increased decentralisation of power generation? Biomass? Tidal/wave generation (potentially quite a good one on our wave-beaten island)? To just say Wind power isn’t working, therefore Nuclear must be the answer seems quite simplified… Admittedly Wind power may not be much use for base supply, but for peak supply it could do a job, and at the risk of sounding like a Tesco advert, every little helps.

    11 Dec 2006, 02:20

  2. How can wind provide the peak supply? It might not be windy at 5.35 when the kettles go on.

    I agree the arguement is simplified, and that decentralised microgeneration would benefit efficiency in houses across the country, though probably only those with older boilers as a modern boiler is already about 90% efficient. Tidal power runs the same NIMBYism that everything else has. A barrier across the Severn would generate nearly 12000MW for 10 hours a day, but the environmentalists don’t want to affect the sealife in that area… but they don’t want greenhouse emissions either… or nuclear… which leaves errr living in caves, without fires.

    11 Dec 2006, 09:48

  3. Paul – I agree that other alternatives also exist. I for one would support a tidal barrier across the Severn, which would generate 4% of the UK’s energy use. As Chris pointed out though, quite often the same people who oppose Nuclear etc are also opposing things like the barrier. We have a baseload of 46GW and we have to generate it somehow; it doesn’t just come out of thin air (pun not intended).

    Increased decentralisation I’m a bit dubious about. For a start, how would decentralised power be generated? Not with micro-turbines it seems! Fossil fuel powered ones would work nicely (CHP boliers) albeit with a much larger logistical problem for the grid than it faces at present, but then we’re not getting away from fossil fuel/CO2 problems. Solar – well PV is pathetic in generation in this country compared to cost, and of course it only works during daylight hours, whereas peak demands usually occur in Winter at tea-time, when there is no light.

    Biomass too has it’s place I agree, but co-firing with biomass is limited to about 10% as a maximum co-firing limitation. Other forms of biomass, such as methane from waste, are pretty good but their supply is limited. As you have said, every little helps, but with all the renewables options we can seriously consider it is just that – a little. With the best will in the world, the vast majority of our demand is not going to be met by renewables in the next 50 years, so we need to think now about how we’re going to generate the rest.

    11 Dec 2006, 13:15

  4. A clear, accurate and unbiased first 80% of this post Sig – so it’s only the last half-paragraph people are going to bother replying to!

    It goes some way to illustrating the pointlessness of spending £1500 (installation included), plus planning permission etc., to get one of those stupid little B&Q DIY domestic wind turbines – which will never pay back their financial cost within their service liftimes and may not even approach repaying their carbon cost either.

    They’re rated at 1kW (about two-thirds of a kettle) in a 12.5 m/s wind, but don’t start generating until it reaches 5 m/s and have to be shut down at windspeeds over 14 m/s. Noise is 33 dB(A) if you’re standing 5 m away with a 5 m/s wind blowing, but rises to 52 dB(A) at 7 m/s, so it must make a real racket at optimum windspeed. Surely that’s louder (and hence far less efficient) than the large-scale towers? Just for a final kick in the teeth, it’s only rated for a ten-year service life under “expected conditions” – i.e. if you actually mount it somewhere it’s likely to see a useful amount of breeze, service life will be much less than a decade.

    11 Dec 2006, 14:05

  5. Haha I know SiY – I just wish people would listen to the unbiased parts every once in a while… As regards micro-turbine stuff, I couldn’t agree more. If the big wind farms aren’t doing their bit, then the micro ones really don’t have a hope in hell of doing so.

    To those who don’t agree with my last, admittedly biased paragraph, I invite you to answer the following. The government’s current target is 60% of energy to be generated by renewables by 2050. How would you go about generating this 60% (about 27GW)? I’m open to any alternative to my suggested option of nuclear and sequestered fossil fuels provided you can prove to a sensibly small degree of uncertaincy that it’s a viable alternative (i.e. cost effective, reliable and actually meets it’s claims of output, unlike wind which, from above, has fallen short under scrutiny), and actually stands half a chance of being developed and built to the required scale within 40 years. My view that nuclear is the way forward is often rubbished, but I’ve yet to hear anyone actually give me an alternative, instead of saying that my vision for the future is wrong.

    11 Dec 2006, 14:17

  6. D Cooper

    Denmark is famously held up as an example of successful large scale installation of wind turbines. But even there it is only remotely justifiable because they can balance the load using Swedish hydro power.
    Finland is building nuclear power stations – they have a long enough memory not to wish to rely on Russian gas. China likewise. I predict within 20 years we’ll but the next geneartion from China – after our cowardly politicians have destroyed our own industry’s expertise.
    The 3 Mile Island accident effectively finished nuclear power in the US – but NOBODY was injured by it.
    Paranoia about radiation has give the UK mad rules about ventilating basments where radium might leak in from surrounding rock. But there is a negative correlation between places where radium can be found and the lung cancers of concern – i.e. low radiation doses are not harmful and might be beneficial to us. That massively alters the safety case. And if you want bombs, you build ‘research reactors’ – like those in universities all around the word.

    11 Dec 2006, 23:52

  7. Our government is at least seeking for new build nuclear (as well as geological repositories for the waste). And it’s not often you hear me say something nice about Labour or Tony Blair! He has the right idea with Nuclear though. I just hope he has the guts to force more unpopular policies through (not been an issue for him in the past!) – the public are wrong on this one. I personally think that the big players nuclear wise will stay as France for PWR’s (the route we will probably take) and Canada for the PhWR’s (a better but more expensive reactor). China’s development of nuclear capability is rapid though.

    12 Dec 2006, 12:37

  8. I like the idea of the radiation cleansing!

    If plastic based PV’s could be made, would be effective if say, close to 50% of households and businesses had solar PV’s on their roofs to provide daytime power? I guess the real source of the problem is still rising population and waste. I think more work needs to be done on the power saving side, before any of the provision of power problems can be solved. My new proposal is to have any digital set-top box that uses more than 1W on standby to be banned from all shops.

    I remember Chris Hinds talking about the wastage of electricity on the Warwick campus illuminating all night. I guess its important to have lighting for safety and security reasons. But I think every flat corridor in Heronbank has 8 flourescent lamps (one can only hope that someone soon makes an affordable LED array to replace all these). Sometimes people will always remember to turn off the TV, yet always have the window open with the radiator on…

    Oh you’ll be pleased to know that they’ve put up 1 or 2 recycling points around campus. So I guess we’re now starting to recycle 0.005% of our waste – yipee!

    12 Dec 2006, 12:48

  9. Why would plastic PV’s be more beneficial Nathaniel? PV’s are currently made of a number of materials using a variety of different processes, varying in expense depending on what efficiency you want to pay for. As regards power saving – well yes we could do more, but again it’s an incremental little bit of a solution and does the good old environmentalist trick of neatly avoiding talking about the bulk of the problem by fussing about the odd percentage point here and there at the fringes. I’m not denying that each and every method of generating electricity (and reducing it’s consumption) has it’s place, but combined these measures still fall massively short of demand. It’s the bulk of generation that I’m talking about.

    12 Dec 2006, 15:19

  10. I was suggesting that plastic PV’s could be made very cheaply, so that it might be an affordable solution even if it has rubbish efficiency (and probably a poor carbon footprint). Wondering if we had enough of this rubbish stuff on our roofs would it be enough to generate a good enough proportion.

    14 Dec 2006, 14:03

  11. I suggest you look at whatever ES368 (Renewable Energy Systems) has been replaced by. I did this course last year, it wasn’t too bad. Anyway, plastics – the problem you’ll face here is that, as I’m sure you know, PV cells are made of rather special materials. A solar cell works using semiconductors (doped materials) to create P and N type semiconductors. These are joined to form PN junctions. What limits solar cell “efficiency” is the band gap of the semiconductor – they have a specific amount of energy required to displace one electron across the PN junction (which causes the electric current to flow), and so can only absorb light in this narrow energy gap in order to produce a current. Doing fancy stuff such as using multiple layers with different band gaps, and using nanotechnology to build structures that are highly effective at capturing photons, can improve the cell’s ability to capture light and convert it into electricity. However these things all bump up costs astronomically. For commercial use (i.e. on your house) you want maximum energy out for minimum cost – note that this isn’t necessarily the most effecient cell (and indeed since we’re getting our fuel for free, we’re not at all bothered about the efficiency), you just want maximum power for minimum cost.

    Anyway, aside from the fact that plastics don’t make semiconductors, you won’t generate a lot of energy from your rooftop PV array. For a start, you have to take into account all sorts of problems like the sun moving around (if your plate is just on the sloping roof, you’ll lose huge amounts of the sun’s energy by it not shining at right angles all the time to your plate) and it’s angle altering during the year. Peak power from a decent but affordable PV might be in the order of 100 watts per square metre on a sunny day. You’d need a lot of area to make a big dent in your home’s electricity usage.

    14 Dec 2006, 16:55

  12. Hero

    Classic case of someone piling up all the negatives, climbing on top of them and thinking he can see jesus.

    A solar panel the size of the average space given to an office worker (10 square feet) will provide enough power to provide heat, light and power a computer for two office workers.. on a flat roof in the UK.

    When you consider that some countries (eg Italy) are not providing enough local power to power their air conditioners in the summer – and that summer is the time of the longest and most powerful solar heat and brightness, you can see why local generation is sensible.

    People don’t really understand how bright daylight is because their eyes adjust.

    15 Dec 2006, 11:48

  13. A solar panel the size of the average space given to an office worker (10 square feet) will provide enough power to provide heat, light and power a computer for two office workers.. on a flat roof in the UK.

    10 square feet is about 1 square metre. On a good day, in summer, at midday assuming the sun is directly above the panel (i.e. at right angles, which it still wouldn’t be if the panel was flat and we’re talking about the UK) then it would provide something like 100 to 150W of power. A computer power supply is typically 300W+, then the screen is at least another 50W for a decent TFT screen, say we’re using efficient lights so that’s another 20W, and we’ll also assume since I’m feeling generous that your heating demands are zero (it’s the middle of the summer after all, and I probably don’t have air con in my office). Power demands we’ll call a ballpark figure of 350W then. Therefore, at peak output (which happens only within a couple of hours each clear, sunny, summer day), one office worker would need in the region of 3 square metres of solar panel. In the winter time (which as I keep on pointing out is where we get peak demands), solar output would be pathetic, meanwhile everyone has the heating on (most people in our office have electric fan heaters or bar heaters, so each one of them is using probably in the region of 1kW extra, which gives an overall demand of about 4 times that in the summer). Additionally, most office workers work in multi-storey buildings, which further reduces the amount of sunlight that any one worker could try and get their energy from.

    I suggest in future you do some thinking before quoting false information – or did you work out your 2 office workers needing 10 square feet of solar panel yourself?

    15 Dec 2006, 12:57

  14. Hero

    well.. resisting the urge to ridicule you .. the first point to make is that a metre is 3.3 ft so 10 sq feet IS 3 sq meters.. dummy! so on your own figures we are talking a peak of around 450W, and perhaps a low off-peak (very cloudy or autumn/winter evenings) of say 250W.

    A well insulated office with an energy efficient computer running in it (20W-50W) and a body in it will need top-up heating for three (perhaps four) months a year. If heating is hot water solar heated or electric underfloor heating, (around 60W) and a 12v lighting circuit installed, enough light can easily be given off with 10W-20W, so we have at the maximum 50+60+20 = 130W per person i.e. 260W for two people with the heating and lighting on.

    Assuming this office is reasonably well-designed, so that daylight can be used with a small top-up lighting on the desk for duller days/evenings, the panel will only need to provide power for the computers and the top-up light for 7-9 months of the year, making a surplus that can be stored in batteries for evening/night/a few dull days, or sent back to the grid.

    Oh and if people in your office are using bar fires then sack them they are wasting company resources – a bar fire is massively inefficient.

    15 Dec 2006, 13:50

  15. Hero

    I forgot to address the point about multi-story – well it goes like this – many office workers also work in one or two-floor buildings, and some in four-floor buldings. Many offices give far more space per person overall than 10 sq m (as there are other functions, corridor space, shared communal areas, stairs etc). Covering the rooves of most office buildings with solar panels would have a dramatic effect on running costs.

    Some consultant you are!

    15 Dec 2006, 14:15

  16. Villan

    Looks like Hero’s confusing “ten square feet”, with “ten foot squared”. Twat

    15 Dec 2006, 14:15

  17. Hero

    Um yes.. thanks villan very er constructive..

    I did put 10 sq m in the last post, but this is fine..

    Ten square feet is the same as ten foot squared, unless you are talking about people with square feet – in which case we are really going into la-la land

    15 Dec 2006, 14:42

  18. Hero

    Sorry I see why this has been confusing. The term ‘twat’ wasn’t helpful – it stopped me reading what you meant.

    10 foot square is the same as 10 foot squared, 10 square feet is not, which is what I said in the first post admittedly, so apologies for that.

    So lets explain properly, beause I still think that the point is valid. In metres squared.

    The average desk worker is given around 3m squared. A solar panel of this size in the UK can provide enough power to supply that worker and a colleague with heating, lighting and a computer, which means that two floor insulated offices with solar-panelled rooves can be self-sustaining.

    15 Dec 2006, 14:56

  19. So by 10 square feet you mean an area of 10 feet by 10 feet – i.e. 100 square feet. Which is about 10 square metres…

    Our different language in units aside, your estimates for energy use are a little off. Apart from heating, your estimates for power consumption of a comptuer barely covers an energy efficient screen. On top of that, you have the power consumption of the desktop station (I would say a minimum of 100W), then for offices like ours the amount used by network and storage servers, printer gear, our high end computational clusters (some of which are 8 processors plus) etc etc.

    Your estimates of how rapidly power output trails off with non-ideal conditions are also way out. On a clear sunny day, solar insolation after getting through the atmosphere is about 1kW per square metre (where the area is normal to the direction of light – imagine a spherical surface surrounding the sun at a distance of 93 million miles, 1 square metre of this area would have about 1.7kW falling on it but that’s before a good amount of it is absorbed by the atmosphere). Now, 1 square metre of the earth’s surface is almost always at an angle to this, so we need to do some trigonometry to get the amount of energy falling on 1 square metre of earth. To work this out, we need the Zenith angle – the angle from directly overhead to the sun’s position in the sky. This is dependent on latitude, hour angle and solar declination angle. Solar declination varies according to season – the equinoxes at summer and winter are +23.5 and -23.5 degrees respectively, with the spring and autumn equinoxes at zero angle. The equation to calculate the zenith angle is:

    Z = inverse cosine (sin(latitude)*sin(declination) + cos(latitude)*cos(declination)*cos(hour-angle))

    Latitude is obviously geographically dependent, whilst hour angle is (15 * (time-12)), where time is solar time (zero at midnight). So we have our angles, and so we can work out our zenith angle. The insolation on the surface is then simply:

    I = S*cos(z)

    Where S is the solar insolation I discussed earlier (about 1kW per square metre). So, assuming clear weather conditions, here’s some rough insolation figures for you for the UK (latitude 54 degrees):

    Midday sun, summer equinox – approx 860W
    3 hours from midday sun, summer equinox – approx 700W
    6 hours from midday sun, summer equinox – approx 323W

    Midday sun, spring equinox – approx 590W
    3 hours from midday sun, spring equinox – approx 415W
    6 hours from midday sun, spring equinox – 0W (sunset)

    Midday sun, winter equinox – approx 215W
    3 hours from midday sun, winter equinox – approx 60W
    6 hours from midday sun, winter equinox – 0W (nightfall)

    Bear in mind that these insolations then have to be multiplied by the efficiency of your solar panel to get the power output (and by a weather factor to account for cloudy days). Most cells are crystalline silicon (unless you really want to spend mega-bucks on solar cells, this is as good as you’re going to get), typically you might expect 12% in reality or up to just shy of 18% for a really fancy (read: expensive) cell under lab conditions.

    As regards multi-storey – our building has 14 floors. With the best will in the world, you’re not going to get anything like the amount of energy needed for running our building. Oh and one thing about electric bar fires – technically, as they convert 100% of the electrical energy they absorb into heat, by the definition of efficiency they are 100% efficient.

    15 Dec 2006, 19:49

  20. I have to agree with Chris in post 7.

    Britain needs nuclear power.

    17 Dec 2006, 01:23

  21. Roger

    Did you mean summer and winter solstice Siggy?
    Good mathematical analysis. There’s so much flannel spoken and written about this subject like “up to x% of our energy needs”
    I see they’re going to build a big offshore wind farm in the Thames estuary. It would be interesting to get some real figures on costs and output instead of the usual “enough power to supply x million homes” We want the figure in Gigawatts!!
    Similarly one of my main objections to the nuclear power industry is that some cost figures seem to get “lost” somehow. It’s a well-known fact that Mrs Fatch never privatised the industry because everybody knew that they would never make a profit once costs like safe disposal/decomissioning, security and ongoing R&D were taken into account. Of course, that was then…..

    18 Dec 2006, 09:08

  22. Hero

    1.The most efficient laptop systems run around 20W
    2. I didn’t mention servers, I said a computer, phone and light/heat
    3. Bar fires are not 100% efficient – what do you think the glow is? This is GCSE physics for cripes sake!!!
    4. Bar fires heat most effectively with radiative heat which reduces exponentially with distance from the bar. Sitting very close naked gets the best from them but is unsafe, radiative heat is very inffective at heating air.

    18 Dec 2006, 09:35

  23. Lindsey

    Is it sad that I couldn’t read much after cracking up laughing at Siggy being called a dummy and then Hero being called a twat? Language, children!

    I don’t think that nuclear power is the best solution ever. But I certainly think it is the best solution NOW. I like the idea of using water, wind, and solar power… but it’s not efficient enough yet. But I still think they should be used to semi-lower the usage of nuclear… and to continue trying to improve their efficiency.

    Also – did I tell you that my older brother (so no, I didn’t tell you) works at Bruce Nuclear? They have SO MUCH security there. He was telling us about the guys walking around with guns and the armored vehicles with guns on the top! Oh man I thought it was hilarious. But then, Bruce Nuclear isn’t alllllll that far away from the Meaford Tank Range. So most of the security is ex-military. Like how I am off-topic? Yeah. I’m just not a born debater! ALSO today is Monday. I’ll be in England on Thursday! How exciting. I’m going to be so sleepy.

    18 Dec 2006, 15:13

  24. Another off-topic:
    Computers are 0% efficient. The only thing they do is make heat (and a tiny bit of LED light and noise). Unless the one of the reasons you run them is to produce heat :D

    18 Dec 2006, 19:16

  25. Roger – I did indeed mean solstice. I agree that the information is also badly supplied – we are told “how many homes” they will supply, but expressing this as a percentage of demand would be more useful (although this is perhaps a moot point). What would be better still would be to see the true utilisation factors and output variation characteristics of such an installation, and hear how they are planning on overcoming the technical difficulties of relying on the weather for our power. Cost of nuclear power is a very contentious issue – there is disagreement on all sides as to what nuclear power might cost in the future. Variables include cost of disposal (the best way to dispose of waste would be a geological repository, which we could pretty accurately cost) as well as build, operating and decommissioning costs. One trick a lot of anti-nuclear organisations try to pull is to quote past costs of nuclear as a direct prediction for the future – comparing, for example, old Magnox reactors with new PWR’s. Which is akin to using the running costs of an old and inefficient car of oudated design with a new modern efficient one. If I were to work out the running costs of a 1.8 litre TCDI Focus I wouldn’t use a Ford Anglia as my starting point!

    Hero – I was discussing my office requirements as a typical measure for others. We’re not running laptops (they don’t suit our needs), we have servers, etc etc. I don’t know of any offices where everyone has high effiiciency lighting and ultra-efficient small display laptop computers – do you? The glow you speak of from bar fires is due to black body radiation of the element at high temperature. Given that incandescent (that’s normal light bulbs) lights are essentially exactly the same thing but designed to give off far more light compared to heat than a bar fire, and yet is still only ~ 5% efficient (i.e. a light bulb is a 95% efficient bar fire), I think we can see just how much the glow accounts for. I would hazard a guess in the 0.1% region. Furthermore, unless this glow in some way shines out of the window (it’s at close to infrared frequency mostly too since the spectral power of blackbody radiation changes with surface temperature, and will be highly distributed towards the infrared region for low temperature heating elements), most of that glow will be absorbed by the surface it shines on (mostly the inside of the heater) and then heat that up too, transferring that energy to it’s surroundings… As heat. Bar fires heat primarily the immediate air around them, slightly with radiative but mostly by convective methods (heating air and it rises out of the fire and into the room, drawing in cold air from underneath and circulating heat around the room). If you really want I’ll go do some calculations and we can see just how much energy must be coming out of the bar fire as radiation compared to convection and conduction, but right now I have more important things to do. I happen to be fully aware of GCSE Physics, as well as A-Level, S-Level and beyond. I strongly suggest you think more carefully before making pointed posts (again) and demonstrating yourself to be a fool.

    Lindsey – I remember you telling me something about the Bruce Nuclear power plant, it does ring a bell. Over in Canada, you have some of the best reactors in the world, although about the most expensive to build – the CANDU/PhWR would be my reactor of choice if we were going to build more stations here, but I suspect for fiscal reasons we’ll go PWR instead. The security isn’t hilarious, it’s quite necessary and I’m glad it’s there!

    Nathaniel – computer boxes are pretty much 0% efficient, but then you have the output signals they generate to the monitor/sound card/printer/hard disk as storage. Of course as a fraction of input power this is pathetic, but it depends how much you value the output signal as to if the efficiency is worth it ;-)

    18 Dec 2006, 20:34

  26. hero

    I think that you are still avoiding the issue of solar. It is perfectly possible to run an efficience office on a laptop system. Many do, but the point is not whether existing offices are inefficient, more that future offices can easily be efficient. inneficiency we can taken as read.

    if bar fires were as efficient (i.e. best aailable result fot the least power input) bar fires would be the overriding heater of choice, and would be advocated as the green consumer’s choice. In fact they are the last favoured option, and are favoured by those unable to invest in efficient heating (i.e where the short-term economic impact is minimised, and the long-trem implication maximised).

    if you think that bar fires are effective convection heaters try blocking the immediate radiation between you and the fire and see how dramatic the heat loss is.

    18 Dec 2006, 23:35

  27. Sorry Hero, but Siggy was right and beat me to pointing out that your figures for power consumption were pretty optimistic (allowing only for the lowest-consumption laptop computer, no ancillary support and – at 10-20W per person – little more than per-desk spotlighting at recommended lux levels) and your figures for solar power were wildly optimistic.

    Take your own figures for power consumption, use the equation in comment 19 (or start with the results already calculated) and work out what the payback time would be for 10 m2 of solar panel in whatever material you choose. You can try to include for the cost of battery backup or grid connection with the requisite inverters and rectifiers if you want – pretty expensive – but otherwise bear in mind you won’t be using the peak power provided by the sun and will have to lose the greatest power supply owing to the relative lack of demand – no heaters, fewer kettle breaks. Then compare this cost to length of service life of solar panels and the cost of maintaining them (e.g. keeping them spotlessly clean).

    It’s a facile point but, using your own logic (“if bar fires were as efficient… bar fires would be the overriding heater of choice”), surely everyone would be using solar panels already if they can supply all electric power to a two-storey office?

    19 Dec 2006, 00:39

  28. Hero

    Did I mention costs and payback times?

    Solar is a new and pitchforked-at technology, whereas barfires have been around for years and years. People who consider solar panels are still railed at by people like Mr Siourney, who are nervous about their world view being altered, and by ‘cost experts’ who moan about payback times.

    The contrast is that people who talk about payback times are often working out how long it is before the power becomes effectively free, whereas for supplied electricity, you are always paying.

    If you cojnsider the carbon-footprint point then solar is even more worth it. Also you are forgetting that at the moment the high cost of solar panels is largely a market and demand issue – few demand, so supply is limited, and you have reduced economies of scale.

    I know the ‘status quo’ inertia is difficult to break, and its uncomfortable for people to believe that we are not doing the best things all the time, but that is where we are.

    And by the way, I keep my windows spotlessly clean, and Mr Sigourney claims he does the same with his car – is it really too much effort to clean solar panels?

    You can obtain acceptable lux levels with low watt bulbs, energy bulbs will give out enough light, and spotting around desks is fine.

    19 Dec 2006, 08:54

  29. anonymous


    19 Dec 2006, 08:56

  30. Did I mention costs and payback times?

    No, but whoever is paying for the installation of your solar panels will. The cost of buying the things and whether it’s worth doing so in the long run, make up the vast majority of the drive for the market, not how conservative or radical somebody is feeling.

    whereas for supplied electricity, you are always paying

    Of course you are always paying for mains-supplied electricity, but if you never recoup your initial outlay on solar panels before they reach the end of their service life, you’re out of pocket relative to where you would have been if you had stayed on mains power. If you are likely to make a net saving over a decade or two, it then becomes a cashflow issue.

    I didn’t expect you to take my comparison to bar fires seriously, after I called it a facile point.

    Is it really too much effort to clean solar panels?

    Not too much effort, no, but paying somebody to come and clean them once or more every month – under the Working At Height regulations if they’re installed on your roof – will add significantly to your operational costs, i.e. the energy cost you experience.

    spotting around desks is fine

    You need sufficient lighting in between desks so as to highlight trip hazards etc. (Health & Safety At Work Act). I could dig out some maximum lighting contrast values from the CIBSE guides but suffice to say installing lights only above desks is a non-starter (and restricts your office to one possible layout).

    at the moment the high cost of solar panels is largely a market and demand issue

    Yes, absolutely. Demand is limited by the low power generation (i.e. cost saving) relative to cost price (and lifespan). As we can’t incease the amount of sunshine we get, and don’t want to tip the balance of the equation by choosing to use more electricity, two things will change the demand situation: better technology to manufacture higher-efficiency materials at a cheaper price than they are currently available, and an increase in wholesale and retail prices for mains electricity. The latter has been happening for a good long while, and will continue. At some point, not too far off, the potential savings will start to reach a level which make the most cost-efficient renewables attractive. The growth cycles of increased purchases, cheaper volume production and more cash into technological R&D will then kick into action. Arguably this is already happening – but, as demonstrated by my comment 4 – media hype and image concerns can also make people decide to make the jump too early or to the wrong technology entirely.

    19 Dec 2006, 15:04

  31. Hero

    Ok.. but a lot of what you are saying is weakened because it relies to heavily on the economic man argument. there are many many negatives to everything and even more so to 240v electricity.. imagine if the change were the other way..

    your bleats would be.. Imagine what would happen if you were electrocuted! . you are forgetting the cost of having to get an electrician to install it! what happens when something goes wrong with the supply stations! H& S dicates that you have to have your meters tested regularly! Why would you give control of your power to an external source! what about terrorism! why have high voltage under the streets.. isn’t that dangerous?
    what about the concentrations of pollutions at single sites??.. have you forgotten about the heat that comes off incandescent bulbs! dont things bust into flames if they touch a bar fire!

    19 Dec 2006, 15:21

  32. I don’t really understand your first statement about weakening my argument by depending on the economic aspect: I’ve only been talking about the economic aspect of photovoltaics, naming it as the reason that take-up of solar panels has been pretty scant so far. It’s the only reason one really can object to photovoltaics: they’re low maintenance, pretty invisible on a roof, a nice supplement to mains power which doesn’t interfere with other supply sources, and fairly low-carbon, etc.

    The reason we don’t all have this free energy device installed isn’t an ideological one, it’s because we’d have to pay a lot of money for the panels to start with, and fixed flat panels currently (or perhaps only until very recently) do not generate enough power in the UK, over their lifetime, to justify their purchase cost.

    For the record, if we were changing from PV to 240V AC, I’d probably welcome the chance to boil the kettle at any time other than noon on a summer’s day and to know that I’m not going to have to sit in the dark after sunset.

    19 Dec 2006, 17:49

  33. Bar fires – most people don’t use electrical heating, but use fossil fuels (gas or oil) to heat their homes instead. It’s not hard to work out why – the energy you get to your home has typically come from natural gas, which we need to burn say three times as much as the amount of electricity ending up in our homes due to losses in generation and transmission (i.e. 3kW worth of gas at power station for 1kW of electricity at home). When you consider that we can just burn the gas direct at home and achieve much higher efficiencies for generating heat, it’s no small wonder that fossil fuels direct work out cheaper fiscally as well as environmentally. When electrical heating is used, it is usually an electrical fire with some sort of fan. This has nothing to do with the efficiency of heat generation – the element works exactly the same as it does in a non-fan assisted electrical heater. It is merely that the fan can circulate heat around the room better and direct it to where the occupants are, thus achieving a more uniform room temperature/reducing energy use by directing heat. But the efficiency is no different, in fact because the fan requires power too it’s a little worse.

    As regards solar panels – there is in fact huge demand for them at present (in this country anyway). Costs are also falling – it’s one of the old rules of manufacturing – as you build more of something the build cost decreases as it moves from specialised product to efficient mass production. However, they at present represent a very daft idea as a reliable electricity source for three reasons. Firstly, as we’ve already discussed, payback times are often longer even than the life expectancy of the panel, so fiscally they make no sense. Secondly, the amount of initial energy required to make these panels is high, so environmentally the embodied energy in manufacture compared to the meagre output you generate is expensive – that is, they aren’t “free” to the environment either. Thirdly – they cannot meet demand levels for electricity consumption, both in quantity and 24 hour availability. Batteries add masses more onto financial cost, embodied energy (and therefore environmental cost) and system complexity.

    I am, in fact, a big supporter of solar energy in countries where it makes sense. In California for example they have a large solar power station (called SEGS) consisting of parabolic reflectors and oil tubes that generate electricity by heating the oil from concentrated sunlight (much cheaper than PV). Devices such as “power tower” stations, which concentrate solar energy with reflectors onto a small array, and solar updraft towers, which have the ability to generate power at night as well due to the storage of solar energy as thermal at the base of the tower, make a lot of sense as the energy is pretty reliable, cheap (because more sunlight power = more power = cheaper electricity for the same kit) and we can pretty accurately predict variations in power output as weather etc is much less of a factor in places like California. But electricity from solar cells at our lattitudes with our climate? Not until we see a step change in technology and/or climate!

    19 Dec 2006, 19:51

  34. hero

    good,so now we admitting that solar power has some merit, but is tight to the wire on being efficient in the UK, and that largely the arguments against are based on the high energy costs of production and the payback time.

    Now compare your assertions with similar assertions for local use of wind power… the energy costs of production of units are very low, and payback times (assuming you have some basic maintainance skills) are vastly exceeded by lifespan.

    19 Dec 2006, 23:06

  35. Where does what “we are now admitting” contradict what either Chris or I have said so far on solar?

    Wind power… here we go… the answer to your question/challenge hinges critically on what you mean by “local”. If you mean a B&Q kit on somebody’s terrace-house chimney in Knightsbridge, no it’s not worth it. Read comment 4 in conjunction with Chris’s article, and do not pass Go.

    If you’re talking about a remote off-grid location, where money is effectively no object owing to the potential benefit from electric power and the alternative cost of extending grid power to the site, then the situation may well be right to install a turbine and a very expensive set of batteries or other storage devices. I think, however, it can probably be said that this is a fairly niche case unworthy of too much attention.

    The final possibility, predictably, is the grey area: grid-connected power generating turbines. This really needs to be divided into two categories, namely onshore and offshore (as alluded to by Chris in his initial article). My initial, basic take on it is that onshore turbines are generally of low benefit; offshore installations are more worthwhile owing to higher utilisation, despite their significantly greater construction, installation and maintenance costs; both categories face the problem that, as the proportion of UK power generated by wind increases, the more conventional generating equipment you need running on “hot standby” to cover medium, high and very high frequency fluctuations in total grid supply. Therefore, from a policy point of view in the short-to-medium term, tidal and wave power are better bets to form a significant proportion of UK renewable generation, along with more conventional renewables such as biofuel in its various guises.

    20 Dec 2006, 00:11

  36. Hero

    You are confusing ‘what’s possible’ with ‘what’s available through a major retailer’ a common British problem

    20 Dec 2006, 08:34

  37. Bob Irving

    All of the above starts from the premise that the Renewable Energy Foundation (REF) is in favour of windpower, which it is not! It give every sign of being a front for a group in favour of gas turbines and is run by someone who objected to a wind turbine being built close to his house. So their numbers are a perhaps a little less dependable than might be thought….

    20 Dec 2006, 10:04

  38. Lindsey

    Oh! Did I ever tell you we have wind turbines in Ontario? There’s some somewhere near Orangeville at least and some up near Wiarton (forget where exactly they are). It looks like aliens landed when you drive past… middle of farms… and then… white wind turbines going round and round…

    I guess Ontario tries to compensate a bit with natural things! Buuuut at least we have nuclear reactors too. We’ve chatted about this before at some point I think.. you were suprised that I’m pro-nuclear. It’s because I’m anti-natural gas ;) And recognize that it’s gonna run out and really, we need something that can actually take over the role that gas has… which right now, the more natural ways of attaining energy just can’t do. Did that make sense? I want to go back to bed!

    20 Dec 2006, 11:36

  39. Hero – I never said that PV solar power was without merits, just that in this country it is wholly unsuitable. And it’s not just me saying this – many engineers who are deeply concerned with environmental issues agree with this analysis (I think I am right in saying that both Colin Oram and Brett Martinson think PV is mad in this country SiY?). As regards wind power – the payback times both fiscally and environmentally are usually very large for domestic sized units – they also don’t tend to have very long life spans. Commercial wind farms, on the other hand, especially those located offshore when the utilisations are high, have good potential for energy payback. However, as I pointed out in my original article and have been pointing out since, large variation in maximum output causes hell for the national grid and requires a large percentage of spinning reserve when the wind isn’t blowing (spinning reserve being power stations that are operating but not under load, and are called in at short notice to meet fluctuations in demand and output from other power stations). This raises costs and increases environmental impact. I don’t think that myself or SiY are confusing what is possible with what is available – we are both highly qualified and competent engineering graduates. Perhaps we should enter your world of what is possible though and design some sort of perpetual motion electricity generator?

    Lindsey – I do know that you have wind turbines in Ontario (I think Canada was/is one of the leading VAWT manufacturers) although I don’t remember you telling me that! Good to have your input on one of my serious blogs :-)

    20 Dec 2006, 12:46

  40. Bob – do you actually have any evidence to support your allegations that the REF are backed by a pro gas turbine lobby group? It’s important to investigate bias obviously, but just because a group comes out speaking against wind turbines doesn’t necessarily point to them being backed by a group with interests elsewhere – it’s important to consider the possibility that they might actually be right…

    20 Dec 2006, 12:51

  41. Lindsey

    Next time you’re here I’ll figure out a way to do a road trip! And then you can see the turbines. Actually I’d rather take you up to Tobemory. But the turbines are between here and there so it’s ok. haha.

    Also I got the anti-spam question wrong. I wrote orangeville instead of orange. Whoops!

    20 Dec 2006, 14:28

  42. Amusing that Sig’s Comment 39 is simply a re-wording of my Comment 35! Clearly we’re thinking along the same lines on this one.

    You are confusing ‘what’s possible’ with ‘what’s available through a major retailer’ a common British problem

    A shame, “Hero”, I thought you were interested in discussing renewable energy. Instead you ignored the main area of societal and technological interest and aimed for an cheap put-down on a very minor application of wind power. If there’s a significantly better domestic kit on the market, I haven’t heard of it. More importantly: given the size, noise, weight & limitations of these small units (ref. planning permission, environmental disturbance and structural loading), it will take a very large step in efficiency for similar domestic products to become worthwhile.

    Presumably, though (if that was the most significant response you could make to my comment), this means we’re in broad agreement on the efficacy of the B&Q kit and in our opinions of solar power, off-grid installations and commercial grid generation turbines.

    20 Dec 2006, 17:27

  43. All of the above starts from the premise that the Renewable Energy Foundation (REF) is in favour of windpower, which it is not!

    All of the above starts from the premise that REF is in favour of renewables (see the start of the article’s second paragraph), which it demonstrably is. Looking through the group’s previous press releases – it’s not hard: click “Press Archive” on their website – there are notices supporting various Government initiatives as well as tidal and wave energy, biomass, biofuel and even offshore wind generation. Solar isn’t mentioned anywhere I can see, possibly because it’s fairly negligible in the UK at the moment relative to the other technologies. The only thing towards which opposition is expressed is the proliferation of onshore wind farms, which in many non-experts’ view – including that of much of the Government – is the prime manifestation of “renewable energy”. The REF’s position is that onshore wind generation is currently being given unduly strong political credit (50% of Government renewable subsidies, according to REF) relative to its potential beneficial effects.

    It give every sign of being a front for a group in favour of gas turbines…

    What are all these signs, other than a considered opposition to one single form of renewable generation? They’re certainly not very good at promoting gas turbines.

    I hadn’t heard of the REF until Chris’s post last week – it’s certainly not a big or mainstream group – but from what I’ve seen, it has a sounder grasp than most campaigning organisations I’ve come across of the real-world (i.e. technological and economic) aspects of renewable power generation.

    Funnily enough, the REF’s findings coincide fairly closely with informed opinions independently developed by Chris and I. Both of us are MEng graduates in Mechanical Engineering; we have both followed multiple degree module courses on various forms of renewable energy, which were taught positively, enthusiatically and thoroughly by lecturers with PhDs and field experience; and we both have professional and personal interests in the energy industry. Those informed opinions have been expressed above, in part, and (I stress) independently, and so far nobody has successfully challenged any of the figures we have presented, or indeed our interpretations of them.

    As I hope I made clear in my comment 35, I welcome all sensible discussion of and challenges to the opinions and conclusions I’ve stated.

    20 Dec 2006, 17:28

  44. Hero

    be careful when you say ‘professional and personal interests in…’ this is worringly close the car industry doing a report on the inneffectiveness of the electric car…

    Especially interesting given the fact that you can make an eletric vehicle that out-perfoms a Porsche

    21 Dec 2006, 23:54

  45. You can make an anything that outperforms an anything else if you have enough budget and motivation. But whether other things (e.g. vehicle range, comfort and luggage space) have to suffer to achieve that goal is another question – by which I mean horrendously off-topic. The time for electric vehicles may come (more as a stop-gap than an end goal) but we’re not quite there yet, and if we start talking about vehicle technologies Siggy will be off and there’ll be no stopping him! (See any of a dozen of his previous entries with extensive comment threads, and get involved there if you must).

    By “personal interest” I meant that we are interested enough that we use a little of our free time to read articles we spot while browsing newspapers, Institute of Mechnical Engineering publications we get sent, etc., and a little more of our free time discussing the issue every now and then (although generally not with each other).

    By “professional interest” I meant that we both work in the energy industry, in separate branches, and so have a good grasp of the major concepts we’ve been discussing here, and the relative importance of the various factors involved. I am currently working on gas emissions reduction related to the national gas transmission system (by a shift in technology type, as it happens), but I feel no personal affiliation at all to fossil fuels. The days of “a job for life” are well over, and engineers are generally a fairly pragmatic bunch: one reason I’m working where I am is that there will always be an energy industry – the technology may well change, indeed I hope it does when the time is right, but my skill set, and that of a large majority of engineers in the sector, is such that moving into renewables will not be any great problem.

    22 Dec 2006, 11:58

  46. Why hasn’t anyone said anything about ground source heating/cooling?!

    31 Dec 2006, 15:07

  47. Primarily because we’re discussing wind power and electricity generation! Using technologies such as solar hot water and ground source heat pumps have potential to reduce electricity demand and carbon emissions though. A bit of a seperate discussion!

    31 Dec 2006, 16:23

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